The long-term goal of the proposed research project is to elucidate the precise molecular mechanism leading to cholesteryl ester accumulation in the arterial wall which is observed during the atherogenic process. In view of the fact that cholesteryl ester synthesis and hydrolysis in the arterial cell are implicated in the arterial deposition and accumulation of cholesteryl esters, together with the possibility that cholesteryl ester synthesase and cholesteryl ester hydrolase activities may be hormonally controlled (via cyclic 3',5'-adenosine monophosphate and cyclic AMP-dependent protein kinase) we specifically propose to study: (a) effect of cyclic AMP stimulation on arterial wall protein kinase activity, on cholesteryl ester synthesase and hydrolase activities; (b) effect of short-term and long-term dietary cholesterol administration on arterial wall protein kinase activity, on cholesteryl ester synthesase and hydrolase activity; (c) effect of arterial protein kinase on arterial cholesteryl ester synthesase and hydrolase activities in vitro. The studies will be conducted using aortic tissue from normal rabbits and rabbits on an atherogenic diet (diet with 1% cholesterol).